annular boundary的用法和樣例：
例句
- The boundary condition on the body is transfered to body axis.
物面邊界條件被轉移到物體軸上。 - Moreover, the sound pressure and velocity on the virtual boundaries can be get simultaneity by using this method, which cannot be done by conventional boundary element method.
同時採用文中的方法還可以同時得到聲場中非物面邊界上質點的振動速度和壓力，這是常規邊界元法無法做到的。
